1. Field of the Invention
This invention relates generally to medical devices, and, more particularly, to contact connectors used in implantable medical devices.
2. Description of the Related Art
Since their earliest inception some forty years ago, there has been a significant advancement in body-implantable electronic medical devices. Today, these implantable devices include therapeutic and diagnostic devices, such as pacemakers, cardioverters, defibrillators, neural stimulators, drug administering devices, among others for alleviating the adverse effects of various health ailments. Today's implantable medical devices are also vastly more sophisticated and complex than their predecessors, and are therefore capable of performing considerably more complex tasks for reducing the effects of these health ailments.
A variety of different implantable medical devices (IMD) are available for therapeutic stimulation of the heart and are well known in the art. For example, implantable cardioverter-defibrillators (ICDs) are used to treat patients suffering from ventricular fibrillation, a chaotic heart rhythm that can quickly result in death if not corrected. In operation, the ICD continuously monitors the electrical activity of a patient's heart, detects ventricular fibrillation, and in response to that detection, delivers appropriate shocks to restore normal heart rhythm. Similarly, an automatic implantable defibrillator (AID) is available for therapeutic stimulation of the heart. In operation, an AID device detects ventricular fibrillation and delivers a nonsynchronous high-voltage pulse to the heart through widely spaced electrodes located outside of the heart, thus mimicking transthoratic defibrillation. Yet another example of a prior art cardioverter includes the pacemaker/cardioverter/defibrillator (PCD) disclosed, for example, in U.S. Pat. No. 4,375,817 to Engle, et al. This device detects the onset of tachyarrhythmia and includes means to monitor or detect progression of the tachyarrhythmia so that progressively greater energy levels may be applied to the heart to interrupt a ventricular tachycardia or fibrillation. Numerous other, similar implantable medical devices, for example a programmable pacemaker, are further available.
Regardless of the exact construction and use, each of the above-described IMDs generally comprise certain primary components: a control circuit, an output circuit, a power source and a hermetic feedthrough. The control circuit monitors and determines various operating characteristics, such as, for example, rate, synchronization, pulse width and output voltage of heart stimulating pulses, as well as diagnostic functions such as monitoring the heart. An output circuit generates electrical stimulating pulses to be applied to the heart via one or more leads in response to signals from the control circuit.
The power source “powers” both the low-power control circuit and the high-power output circuit. As a point of reference, the power source is typically required to provide 10-20 microamps to the control circuit and a high power pulse to the output circuit. Depending upon the particular IMD application, the output circuit may require a stimulation energy of as little as 0.1 Joules for pacemakers to as much as 40 Joules for implantable defibrillators. In addition to providing sufficient stimulation energy, the power source must possess a low self-discharge to have a useful life of many years, must be highly reliable, and must be able to supply energy from a minimum packaged volume.
The various components of an implantable medical device require electrical connectors that can provide a secure electrical path. The connectors must provide a complete, non-corrosive, and preferably economical means of linking the various electrical components of the medical device. Any incomplete connection of the electrical components within the implantable medical device may cause the device to function improperly or otherwise cause it to cease operating altogether. In addition, because the medical device is surgically implanted within the patient's body, accessibility to the device is difficult for repair or replacement subsequent to implantation. If the implantable medical device functions improperly or fails altogether as a result of an incomplete connection, it may prove fatal to the patient.
Typical connectors in use today comprise a base metal that can have a plating of a second material applied that has certain desired properties such as corrosion resistance. The plating material can comprise specialty metals such as nickel or gold that is applied using an electrolytic plating process. Currently, individually manufactured contacts are used for the electrical connectors in implantable medical devices. These individual connections can collectively comprise a substantial expense and take considerable time to position and secure within the device or component housing. A typical medical device such as a pacemaker or a neural stimulator will have multiple electrical connections between components, each requiring its own physical connection. Thus, with an increase in the number of electrical connections that are made within a particular device, more time and expense may be spent making the required connections between components. Having a number of individual connectors placed, secured and connected between the various components of an implantable medical device may increase the device failure rate, since multiple steps are required within the process.
There is a need for improved electrical contact connector design and means of manufacture.